/**
 * Creates color from background color.
 *
 * @param {Color} $bg-color The background color.
 * @param {Percentage} [$contrast=70%]
 * @param {Color} [$default-color=null]
 * @param {Color} [$bevel-text=true]
 * @member Global_CSS
 */
@mixin color-by-background($bg-color, $contrast: 70%, $default-color: null, $bevel-text: true) {
  @if ($default-color != null) {
    color: $default-color;
  } @else {
    @if (lightness($bg-color) > 40) {
      color: darken($bg-color, $contrast);
    } @else {
      color: lighten($bg-color, $contrast)
    }
  }

  @if ($bevel-text != false) {
    @if (lightness($bg-color) < 40) {
      @include text-shadow(rgba(0, 0, 0, .5) 0 -1px 0);
    } @else {
      @include text-shadow(rgba(255, 255, 255, .25) 0 1px 0);
    }
  }
}
